Just like course lessons can be added to a user's favorites, i suggest allowing Forum and Group posts to be marked as favorites list as well, for a user to quickly navigate back to that thread again, via their personal Favorites list.

The use case i envision, is that a user has a personal forum thread as their training logbook, allowing instructors and participants in a trainig group to comment and cheer on their progress.

Then to return them to their personal logbook thread, it would be nice to have them add it to their favorites (or even: an administrator curated playlist especially for that user).

Another option could be to allow users to pin specific forum content to their /feed/ page on a membership site, to easily find it again.